Wyniki wyszukiwania - BazTech

1

Slow flow past a weakly permeable spheroidal particle in a hypothetical cell

Bucha Tina, Madasu Krishna Prasad

Archive of Mechanical Engineering

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2021

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LXVIII, nr 2

119--146

EN

The perspective of the current analysis is to represent the incompressible viscous flow past a low permeable spheroid contained in a fictitious spheroidal cell. Stokes approximation and Darcy’s equation are adopted to govern the flow in the fluid and permeable zone, respectively. Happel’s and Kuwabara’s cell models are employed as the boundary conditions at the cell surface. At the fluid porous interface, we suppose the conditions of conservation of mass, balancing of pressure component at the permeable area with the normal stresses in the liquid area, and the slip condition, known as Beavers-Joseph-Saffman-Jones condition to be well suitable. A closed-form analytical expression for hydrodynamic drag on the bounded spheroidal particle is determined and therefore, mobility of the particle is also calculated, for both the case of a prolate as well as an oblate spheroid. Several graphs and tables are plotted to observe the dependence of normalized mobility on pertinent parameters including permeability, deformation, the volume fraction of the particle, slip parameter, and the aspect ratio. Significant results that influence the impact of the above parameters in the problem have been pointed out. Our work is validated by referring to previous results available in literature as reduction cases.

2

Determination of the dynamic viscosity coefficient of the Stokes viscometer – construction of a measuring set in the Physical Laboratory of the State Higher Vocational School in Tarnów

Wietecha Tomasz, Kurzydło Piotr M.

Science, Technology and Innovation

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2019

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Vol. 5, no. 2

60--65

EN

A Stokes viscometer made and launched by the authors in the Physical Laboratory of the State Higher Vocational School in Tarnów was presented. The construction of the viscometer is discussed and the theoretical description of the physical phenomena occurring there is given. The results of measurements on the device, statistical analysis of the measurement uncertainties and confrontation with the literature value are presented - the obtained results correspond very well to the literature values. A possible further development in the accuracy of theoretical description and experimental measurements related to the ellipsoid analysis of the shape of water droplets was suggested. The didactic aspects of the new experiment in the context of the understanding of molecular physics, especially by students of material engineering, were discussed.

3

Drag force of a porous particle moving axisymmetrically in a closed cavity of micropolar fluid

Madasu Krishna Prasad

Journal of Applied Mathematics and Computational Mechanics

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2019

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Vol. 18, nr 4

41--51

EN

The present paper deals with the problem of an incompressible axisymmetric creeping flow caused by a porous spherical particle in a spherical cavity filled with micropolar fluid. Depending on the kind of cell model, appropriate boundary conditions are used on the surface of sphere and spherical cavity. Drag force on the porous particle in the presence of a cavity is calculated to determine the correction factor to the Stokes law. A general expression for the hydrodynamic force acting on the porous sphere and, hence, for the wall correction factor of the sphere are obtained. The special cases of the porous sphere in viscous fluid, zero permeability solid sphere in micropolar fluid and viscous fluid are obtained in open and closed cavity respectively.

4

Wpływ kształtu cząstek ilastych na wyniki analiz granulometrycznych gruntów spoistych

Gorączko A., Topoliński S.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2018

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Vol. 27, No. 2

142--151

PL

Pomiar wielkości cząstek za pomocą dyfrakcji laserowej (LDA) jest alternatywną analiz hydrometrycznych (HM) metodą oznaczania składu granulometrycznego gruntów. Przy oznaczaniu frakcji najdrobniejszych, o znacznej zawartości minerałów ilastych, zasadnicze problemy wynikają ze znacznej anizotropii kształtu cząstek. W pracy zawarto porównanie wyników oznaczeń wielkości cząstek iłów neogeńskich z Bydgoszczy. Zaproponowano formuły służące do transformacji wyników metody areometrycznej i metody dyfrakcji laserowej dla badanych gruntów.

EN

Laser diffraction particle sizing is an alternative method to determine grain size analysis in soils. However, for particle with high shape anisotropy LDA measurements usually produce different results than traditional hydrometric methods (HM), based on Stokes equation. The article contains the results of analyzes of Neogene clays characterized by significant lithological differentiation in regard to participation the clay fraction particles. The research was conducted for the clay samples taken in Bydgoszcz. A set of equations to transform LDM results to hydrometric results was proposed.

5

Modelowanie dyfuzyjno-bezwładnościowej depozycji cząstek aerozolowych: wpływ oddziaływań krótkiego zasięgu

Podgórski A.

Inżynieria Chemiczna i Procesowa

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2001

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T. 22, z. 3D

1133--1138

PL

Sformułowano uogólniony algorytm dynamiki brownowskiej uwzględniający oddziaływania krótkiego zasięgu pomiędzy stałą cząstką aerozolową i stałą powierzchnią. Podano funkcje poprawkowe do prawa Stokesa dla cząstki w pobliżu ścianki. Przedstawiono porównanie wyników stochastycznych symulacji depozycji cząstek aerozolowych na cylindrycznym kolektorze filtra włókninowego z rozwiązaniami równania dyfuzji - konwekcji. Przedyskutowano wpływ oddziaływań krótkiego zasięgu (oddziaływania hydrodynamiczne cząstka - włókno i siły van der Waalsa) na sprawność depozycji aerozoli.

EN

Generalised Brownian dynamics algorithm accounting for the short-range interactions between a solid aerosol particle and a solid wall was formulated. Correcting functions to the Stokes law for the particle near a solid wall were presented. Results of the stochastic simulations of the aerosol particle deposition on a cylindrical collector in a fibrous filter were compared with the classical solutions of the convective - diffusion equation. Effect of the short-range interactions (hydrodynamic interactions particle - wall, van der Waals forces) on the aerosol particle deposition efficiency was discussed.